Assemblies used to translate motion in a push-pull manner from a remote input, or operator-control, device to an output, or controlled, device include a known variety of cables and linear-to-rotary mechanisms used in automotive, truck, aircraft, recreational and marine environments. These motion transferring mechanisms are often necessary because the most desired location from which to operate the controlled output device is often not adjacent thereto but rather from a remotely located operator-control, or input, device.
More precisely to associate push-pull control devices to a typical installation, an engine or transmission is often located in a confined compartment removed from the area occupied by the operator and any passengers. For instance, the engine and transmission of a vehicle are generally confined under a hood in a compartment separated by a fire wall from the operator/passenger compartment from which the operator remotely controls the engine and transmission. Additionally, the engine, and transmission, are customarily connected to the vehicle frame through flexible mounts, while the operator-control device is generally mounted either directly, or by rigid mounting devices, to the frame. Thus, from installation-to-installation a considerable amount of accommodating adjustment may be necessary to effect the desired connection between the controlled output device and a remotely located operator-control input device.
Motion transmitting arrangements that typically operate in a push-pull manner have been employed for years as cable controls for automatic transmissions, parking brakes, clutches, cruise control devices and shifting devices where such assemblies are not only remote from the operator-control device but also separated such that the interconnection therebetween must follow a non-linear path.
Known motion transmitting arrangements utilize one or more cables that are axially movable in a push-pull manner for operatively connecting the remote operator-control device to an arm, or similar mechanism, that adjusts, shifts, or otherwise acts on the remote controlled device. One example that exemplifies a typical installation comprises the operation of a transmission assembly where the motion transmitting arrangement is attached to an operator-control gear selecting device at one end of the motion transmitting arrangement and a lever arm presented from the transmission shifting mechanism at the other end. A second example would be a carburetor/throttle assembly where a motion transmitting arrangement is attached to an operator-control accelerator at one end thereof and to a throttle actuating mechanism in a carburetor at the other end.
Push-pull control cables to effect the desired interconnection between an operator-control device and a remotely located controlled device are, generally, well known to the art as devices capable of transmitting mechanical motion in either direction by virtue of a cable core when at least the ends of the cable casing are satisfactorily clamped in position.
Although the prior art knows many constructions for push-pull cable casings, one of the most suitable constructions to assure the greatest flexibility and efficiency comprises a plurality of wires laid contiguously in a long pitch helix around the outer periphery of a plastic tube. The helically arranged wires of the casing are maintained in their proper position solely by a plastic cover in the smaller cables and by a reinforcing spread helix of wire, or flat metallic ribbons, in conjunction with the plastic cover in larger cables.
In the above described construction for cable casings the plastic tube which comprises the innermost element not only acts as a bearing for the core of the cable that is slidable within the casing but also acts to protect the casing wires from any natural elements gaining access to the interior of the tube. A plastic outer cover similarly protects the wires as it maintain them in their cylindrically disposed, helical grouping around the inner tube.
Anchor fittings are provided at each end of the casing to provide means for securing the control cable casing in operative position, and a terminal end fitting is also provided at each end of the core to secure the core, respectively, to an operator-control input device and a remotely controlled, output device.
Historically, the ends of the push-pull control cable casing were secured in a fixed location by a clamping device held in place by a plurality of nuts and bolts (or screws) and lock washers. Each end of the core within the casing was connected to an end rod. The other end of one end rod was connected to the operator-control input device--and this was normally effected by a fixedly positioned nut and bolt connection. The other end rod of the second end rod was connected to the controlled output device by a selectively positionable arrangement that typically comprised a clevis that was selectively positionable along the second end rod and secured in the desired location by a lock nut. In turn, the clevis was secured to the operating arm on the controlled output device by a well known pin, washer and cotter pin arrangement.
The aforesaid historic arrangement of securing the push-pull cable core to both the operator-control input device and the controlled output device was replaced by snap-on, snap-off connectors. The snap-on, snap-off connectors utilized to date in the automotive industry, for example, have required virtually as much force to snap-on as to snap-off. In fact, the best known prior art connector acceptable to the automotive industry required 85 Newtons to effect a snap-on and 90 Newtons to effect a snap-off. Other industry standards require that the connector withstand 50,000 cycles under loads of 90 Newtons in a tension/compression testing. Moreover, the connector must also withstand a minimum of 450 Newtons before separation of the terminal end fitting from the end rod occurs.
Industries using push-pull control cables have not been able to achieve a significantly low snap-on force while maintaining the required minimum snap-off force. Nor has it been easy to achieve the desired wear life over the required number of operating cycles--particularly when being subjected to the range of temperatures to which automotive installations would be exposed in actual operation. In addition, the best known prior art arrangements have been limited to three snap-on and snap-off cycles. It must also be appreciated that the structural differences from installation-to-installation virtually assures that it will seldom occur that the axis of the end rod can be perpendicularly aligned with the rotational axis of the operating arm on the controlled output device. As is well known to those skilled in the appropriate art, the prior known terminal end fittings do not accommodate the desired ease of operation when subjected to such misalignment.